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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A quasi-elastic light-scattering technique was used to study the hydrodynamic conformations of antifreeze glycoproteins from an Antarctic fish. Antifreeze glycoprotein is composed of repeating units of Ala-Ala-Thr, with each threonine O-linked to a disaccharide, and it exists as several polymers of different numbers of this repeating unit. Molecular weights of the two major active polymers are 10,500 and 17,500 by such methods as centrifugation and osmotic pressure, but smaller than 20 by freezing-point depression. Translational diffusion coefficients at 20 degrees were 8.35 times 10-7 cm2 s-1 and 6.15 times 10-7 cm2 s-1 for the M-r-10,500 and 17,500 polymers, respectively. Measurements at -0.2 degrees in the presence of ice crystals did not indicate any conformational changes that might be related to the lowering of the freezing temperature. Lowering the temperature of these glycoprotein solutions close to temperatures of freezing caused a decrease in the effective hydrodynamic radius of both active and inactive glycoprotein components.
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PMID:Antifreeze glycoproteins from an Antarctic fish. Quasi-elastic light scattering studies of the hydrodynamic conformations of antifreeze glycoproteins. 116 94

Neuropsychiatric disorders such as anxiety, depression, migraine, vasospasm and epilepsy may involve different subtypes of the 5-hydroxytryptamine (5-HT) receptor. The 1B subtype, which has a unique pharmacology, was first identified in rodent brain. But a similar receptor could not be detected in human brain, suggesting the absence in man of a receptor with equivalent function. Recently a human receptor gene was isolated (designated 5-HT1B receptor, 5-HT1D beta receptor, or S12 receptor) which shares 93% identity of the deduced protein sequence with rodent 5-HT1B receptors. Although this receptor is identical to rodent 5-HT1B receptors in binding to 5-HT, it differs profoundly in binding to many drugs. Here we show that replacement of a single amino acid in the human receptor (threonine at residue 355) with a corresponding asparagine found in rodent 5-HT1B receptors renders the pharmacology of the receptors essentially identical. This demonstrates that the human gene does indeed encode a 1B receptor, which is likely to have the same biological functions as the rodent 5-HT1B receptor. In addition, these findings show that minute sequence differences between homologues of the same receptor from different species can cause large pharmacological variation. Thus, drug-receptor interactions should not be extrapolated from animal to human species without verification.
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PMID:A single amino-acid difference confers major pharmacological variation between human and rodent 5-HT1B receptors. 143 92

An alanine-rich, alpha-helical antifreeze polypeptide (AFP) from the winter flounder and seven analogs with variations in the arrangement of neutral, polar amino acids were synthesized. Circular dichroism studies determined that all of the peptides, except for one containing a proline residue, were essentially 100% alpha-helical. Freezing point depression data, analyzed by three methods, showed that rearrangement of polar residues resulted in moderate to complete loss of anti-freeze activity. It was observed that ice crystals grow as hexagonal bipyramids in dilute solutions, with a constant c to alpha axis ratio of about 3.3. Above a critical threshold concentration, which may depend on the AFP to ice binding constant and reflect the onset of cooperative interactions, growth ceases until the temperature is lowered to the freezing point. We conclude that a specific arrangement of both threonine and asparagine (or aspartic acid) residues is critical for maximal activity and that the AFPs probably bind to the pyramidal faces of ice with a specific orientation. These conclusions are consistent with a recent report (Knight, C. A., Cheng, C. C., and DeVries, A. L. (1991) Biophys. J. 59, 409-418) that a similar AFP adsorbs to the [2021] pyramidal planes of ice in dilute solution.
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PMID:Structure-function relationships in an antifreeze polypeptide. The role of neutral, polar amino acids. 162 10

The depression of milk protein percentages for cows fed high fat diets in early lactation is a major problem facing the dairy industry. In order to describe more fully the mechanism involved, data involved 97 cows observations were summarized. Cows were fed diets containing corn-soybean meal or additional fat in the form of whole oilseeds as the main ingredients in the concentrate mix. Blood samples from the tail artery and subcutaneous abdominal vein were taken approximately 6- to 8-wk postpartum for amino acid analyses. Production of milk during the week of blood sampling was increased (36.9 and 39.6 kg/d) approximately 7.3% but milk protein percentages (2.91 and 2.79) were reduced for cows fed added fat. Intake of DM (21.1 and 21.4 kg/d) and BW (605 and 608 kg) were similar. Uptake of amino acids by the mammary gland, as measured by arteriovenous differences, was numerically lower for all essential amino acids and significantly reduced for histidine, isoleucine, leucine, phenylalanine, threonine, valine, and total essential amino acids for cows fed added fat. It is proposed that added fat inhibits somatotropin release from the anterior pituitary, thereby reducing mammary gland uptake of amino acids because of the role of somatotropin in aiding amino acid uptake. Administration of exogenous somatotropin with added fat diets may alleviate milk protein depression associated with such diets.
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PMID:Model to describe and alleviate milk protein depression in early lactation dairy cows fed a high fat diet. 262 49

The effect of tumor-promoting phorbol diesters to potentiate the action of epidermal growth factor (EGF) on cell proliferation is associated with phosphorylation of EGF receptors, acute depression of EGF binding, and inhibition of EGF receptor tyrosine kinase activity. In the present studies, normal human fibroblasts and A431 carcinoma cells were labeled with [32P]phosphate and treated with and without 10 nM 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA). The EGF receptors then were isolated by immunoprecipitation and digested with trypsin. Analysis of the labeled receptor phosphopeptides by reversed-phase HPLC revealed that PMA induces the phosphorylation of a unique phosphopeptide containing [32P]phosphothreonine. Comparison of several chemical and physical properties of the 32P-labeled phosphopeptide with the primary structure of the EGF receptor suggested the identify Lys-Arg-Thr(P)-Leu-Arg. This was confirmed by direct demonstration that a synthetic peptide of this structure comigrates during HPLC and electrophoresis with the 32P-labeled phosphopeptide isolated from the EGF receptors of normal human fibroblasts. The phosphorylated site on the peptide corresponds to threonine-654 of the EGF receptor, which is located on the cytoplasmic side of the plasma membrane nine residues distant from the transmembrane domain. These data indicate that phosphorylation of the EGF receptor in human fibroblasts and A431 cells at threonine-654 may regulate the EGF receptor tyrosine kinase activity and the binding of EGF.
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PMID:Tumor-promoting phorbol diesters cause the phosphorylation of epidermal growth factor receptors in normal human fibroblasts at threonine-654. 298 76

beta-Pyrazol-1-yl-DL-alanine, an uncommon amino acid from plants of the Cucurbitaceae, was fed to mice. Although pyrazole is known to affect the liver enzymes UDP-glucose dehydrogenase, UDP-glucuronyl transferase and UDP-glucuronic acid pyrophosphatase, and also depresses their liver glycogen concentrations, beta-pyrazol-1-ylalanine had no such effects. beta-Pyrazol-1-ylalanine could not be detected in the liver of the experimental animals but was present in the urine. No other change in urinary amino acid content was observed. Studies with [14C]-beta-pyrazol-1-yl-DL-alanine showed the administered amino acid was excreted over a 4-day period, 93% of the compound supplied was recovered. Similar recoveries were obtained with the L-enantiomer from cucumber seed. The metabolic inertness of beta-pyrazol-1-ylalanine was also apparent in experiments involving subcutaneous injection of this compound. Administration of pyrazole confirmed an earlier report of resultant increased activity of liver UDP-glucose dehydrogenase and UDP-glucuronyl transferase, and of the depression of activity of liver UDP-glucuronic acid pyrophosphatase. A concomitant 40% decrease in liver glycogen content was seen. The urine contained a novel metabolite, identified as a peptide conjugate of a pyrazole derivative. Mass spectrometry and p.m.r. spectroscopy indicate that this derivative is 3,4,4-trimethyl-5-pyrazolone. The amino acid constituents are aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, valine and leucine. The urine of mice receiving pyrazole contained less free glycine and alanine than controls. From the results, it is concluded that pyrazole is not a catabolite of dietary beta-pyrazol-1-ylalanine but to the contrary, the amino acid is essentially excreted unchanged. Formation of 3,4,4-trimethyl-5-pyrazolone from pyrazole would imply C-methylation, a process that has not been previously observed in a mammalian detoxication context.
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PMID:Metabolism of the amino acid beta-pyrazol-1-ylalanine and its parent base pyrazole. 298 41

Monoamines and amino acids were measured in anterior prepyriform cortex (PPC) and anterior cingulate cortex (CC) of male Sprague-Dawley rats after they were offered basal, imbalanced (IMB) or corrected amino acid diets, limited in threonine (THR) or isoleucine (ILE). In the THR study, brains were taken after 2.5 hr of feeding, when intake of THR-IMB was just depressed. In the ILE study the brains were taken after 3.5 hr on ILE-IMB, a less severely imbalanced ration, before the onset of food intake depression. The PPC has been shown to be involved in the acute response of animals to imbalanced amino acid diets. In the PPC from the IMB diet groups, NE was reduced by 30%, but the other monoamines were unchanged. In CC, an area involved in the adaptive, but not the acute feeding response to imbalanced diets, the monoamines were unchanged in the IMB diet groups. In both studies, in both tissues, the limiting amino acids were decreased in the IMB groups, although the decrease of ILE in the CC failed to reach significance. The remaining indispensable amino acids, added to create the imbalance, were slightly reduced in the THR-IMB group, but not in the ILE-IMB group in both tissues. Thus, the amino acid patterns were altered in the PPC and CC, as they are in whole brains from animals fed imbalanced amino acid diets. These results also suggest that the concentration of NE in the PPC may be associated with the initial food intake response of animals to imbalanced amino acid diets.
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PMID:Norepinephrine and amino acids in prepyriform cortex of rats fed imbalanced amino acid diets. 308 22

Rats were trained to eat a 6% casein basal diet during a 3-hour period per day. They were then fed either the same 6% casein diet or a 44% casein diet for 3 hours. No food intake depression was observed in the rats eating 44% casein diet during the 3-hour period. Plasma ammonia and amino acids and brain amino acids were measured at 0, 4, 12 and 24 hours after presentation of the 6% or 44% casein diets. Plasma ammonia rose to 134 (p less than 0.01) and 110 micromolar (p less than 0.05) in the 44% casein fed rats at 4 and 12 hours, respectively, as compared to 67 and 53 micromolar, respectively, for the 6% casein fed rats. All plasma amino acid concentrations except methionine and glutamate were elevated (p less than 0.05) at 4 hours. In the brain, threonine, glutamine and tyrosine concentrations were elevated (p less than 0.05) at 4 hours after diet presentation. At 24 hours, valine, isoleucine, leucine, phenylalanine, and methionine concentrations were also elevated (p less than 0.05). Because intake of the 44% casein diet decreases the second day of its presentation, as noted in an earlier experiment, the increases in plasma ammonia and its possible entry into the brain as reflected by increased brain glutamine together with changes in amino acid concentrations should be considered collectively among possible metabolic signals affecting intake of high protein diets.
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PMID:Increase in plasma ammonia and amino acids when rats are fed a 44% casein diet. 320 Sep 19

Two 12-day experiments were conducted with Large White turkeys to determine which amino acids are deficient in a diet containing dehulled soybean meal as the sole source of protein. A 22% protein basal diet composed of 43.3% glucose monohydrate, 45.4% dehulled soybean meal, .5% DL-methionine, 6% stabilized fat, and added minerals and vitamins served as the negative control. Two positive control diets were formed by substituting either 16.5% dehulled soybean meal or a mixture containing amounts of essential amino acids equivalent to those in the added dehulled soybean meal in place of an equal amount of glucose monohydrate in the basal diet. Nine additional diets were formed by removing one or more amino acids from the mixture. Each of the 12 diets in a block design was fed to two pens of males and two pens of females with 8 birds per pen from 7 to 19 days of age in each experiment. Average body weight gain of poults fed the 22% protein diet with added amino acids approached that of poults fed the 30% protein diet (288 vs. 300 g, respectively). Removal of the amino acid mixture from the 22% protein diet depressed body weight gain by 19.0%. Depressions of 19, 16, 11, 7, and 6% in body weight gains resulted from the removal of valine, threonine, lysine, phenylalanine (or tyrosine or glycine), and isoleucine, respectively. A decrease of 5% was required for significance (P less than or equal to .05). When evaluated by this deletion technique, effects of valine and threonine deficiency were more pronounced than effects of lysine deficiency in dehulled soybean meal for young turkeys.
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PMID:Deficient amino acids in protein of dehulled soybean meal for young turkeys. 344 40

Several chick bioassays were conducted to evaluate means of ameliorating ethionine toxicity. Supplementing a corn-soy diet marginally deficient in sulfur amino acids (methionine + cystine) with .075% D,L-ethionine reduced weight gain in 8-day-old chicks by 70% compared to gains of unsupplemented controls. Dietary addition of .50% DL-methionine prevented reduction in weight gain and feed intake resulting from ethionine supplementation whereas feeding supplemental L-cystine was without effect. Supplementation of the ethionine-containing diet with either choline or betaine ameliorated the growth depression, although neither compound was able to completely overcome the toxic effects of ethionine. Dietary ethionine did not affect plasma levels of free methionine or cystine but did increase plasma free glycine 6-fold. Dietary addition of .50% DL-methionine caused normalization of plasma glycine levels whereas it elevated plasma methionine concentration. Although results suggested the possibility of ethionine-induced serine or threonine deficiency, dietary additions of .75% L-serine or .75% L-threonine failed to improve chick weight gain. These studies suggest that ethionine, in addition to affecting transsulfuration and transmethylation activity may exert specific effects on certain amino acids in tissue pools.
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PMID:Amelioration of ethionine toxicity in the chick. 365 79


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